Observations of ground and structure movements for compensation grouting during tunnel construction at Waterloo station

Abstract

A new escalator tunnel and associated passageways have been constructed at Waterloo station in London, passing only a few metres beneath two sensitive masonry structures. Compensation grouting was undertaken in the ground between the tunnels and the overlying structures to limit settlements to acceptably small levels. This comprised injections of grout during tunnelling in response to detailed observations of ground and structure movements. The observational method was used in the control of the compensation grouting operations. This was achieved by comparison of field observations with defined limits of acceptable behaviour, and by planned contingencies in the event that these limits were approached. The extensive instrumentation installed to monitor the movements of the ground and the structures during tunnelling is described. Details are given of the performance of the instrumentation, of the measurements made and of the interpretation of the observations required to evaluate the soil-structure interaction behaviour. The specified requirements for compensation grouting and a summary of the grouting operations are presented. Settlements of the structures due to tunnelling were restricted to less than 15 mm. The relatively novel technique of compensation grouting has proved very successful in limiting settlements. Un nouveau tunnel d'escalator et les couloirs associés ont été construits à la gare de Waterloo, à Londres. Ils passent quelques mètres seulement au dessous de deux structures de maçonnerie particulièrement sensibles. Un coulis compensateur a été injecté dans le terrain entre les tunnels et les structures sus-jacentes pour limiter le tassement à des valeurs faibles acceptables. Ceci consiste à injecter du coulis lors du percement du tunnel en fonction d'observations minutieuses de mise en mouvement du terrain ou des structures. La méthode d'observation a été utilisée pour contrôler la mise en place du coulis compensateur. Ceci a été réalisé en comparant les observations de terrain à des limites définies de comportement acceptable, et en parant à l'imprévu au cas où ces limites seraient approchées. On décrit l'instrumentation mise en place pour enregistrer à la fois les mouvements du terrain et ceux des structures. On détaille les performances de cette instrumentation, les mesures réalisées et l'interprétation des observations permettant d'évaluer l'interaction sol-structure. On présente également les conditions requises et le résumé des opérations de mise en place du coulis compensateur. Le tassement des structures dû au tunnel a été inférieur à 15 mm. La technique du coulis compensateur s'est donc révélée efficace pour limiter les tassements.

Contributions to Géotechnique 1948–2008: Tunnelling

“…The latter is often associated with the more recent technique of 'compensation grouting' used to control tunnelling-induced settlements. A paper by Harris et al (1994) describing one of the first uses of compensation grouting is discussed later.…”

Underpinning of shallow foundations by expansive polyurethane resin injections. Case study: Cardinal Diego de Espinosa Palace in Segovia (Spain)

“…Consistent with the above, it can be concluded that after injecting Geoplus expanding polyurethane resin the volume of treated soil does not modify the rigidity or distribution of force under the treated area. In other words, there is no creation of "hard points" in the soil and the procedure for injecting resin can be considered suitable for partial or localized treatment (Henderson, Taylor, Harris, Mair, & Love, 1994) (Manassero, Dominijanni, Foti, & Musso, 2013).…”

Tunneling-Induced Settlement Evaluation for New Tunnel Underneath Existing Tunnel

“…For instance, the pipelines, pile foundation, tunnel, and other facilities were found to be affected by the tunneling underneath them (Vorster et al 2005;Harris et al 1994). It is assumed that the shape of the subsurface settlement profiles can be characterized by a Gaussian distribution (see the lower curve in Fig.…”